The effect of metabolic processes of Bacillus subtilis on mechanical properties and water absorption of concrete

In recent years, new methods for improving the mechanical and durability properties of concrete have been studied and researched. One of these methods is the use of a special type of bacteria that can repair the concrete with their performance inside the concrete.For this purpose, Bacillus subtilis PTCC 1254 strain was used. Adding any unusual material to the concrete should not adversely affect the properties of the concrete. To investigate these effects, 6 mixing designs were investigated. The control design, which is expressed in the text as N; It has been proposed without any bacteria or additives. In the mixing desing called BU, bacteria are added to the concrete mix water with a concentration of 108 cell/ml. Also for bacteria anaerobic function and urea decomposition for produce calcium carbonate, Yeast extract, urea and calcium nitrate are added to the mixture. The mixing design, called BL, contains bacteria with a concentration of 108 cell / ml, yeast extract and calcium lactate. In other mixing design, the bacterial effect alone (B), the lactate effect (L) and the urea effect without the presence of the bacterium (U) are investigated. To investigate the effectiveness of these materials, 28- and 90-day compressive strength tests as well as concrete water absorption were taken. The results of this study showed that the bacterium did not have a negative effect on the properties of concrete. Also, the bacteria with calcium lactate improved the mechanical properties and permeability of concrete.